Nerodog's suggestions are good. As you might image, the foliage season tends to run sequentially from the north to the south and the timing of full color from area to area can be a little unpredictable - as can the intensity of color. Rainfall amounts during the summer and early fall temperatures - among other weather-related issues - contribute to the richness, or lack of richness, of fall color.
The Vermont mountain route that Nero mentioned - Route 100 - runs from near the Canadian border hugging the Green Mountains almost to Massachusetts. For other northern New England areas, both Maine and New Hampshire offer similarly stunning foliage views - as does New England's neighbor through the Adirondack's of New York. The Berkshire's in western Massachusetts are roughly the continuation of Vermont's Green Mountain range and are absolutely beautiful in full foliage as well.
Vermont's timeshares are small in number - look to Sugarbush, Smugglers, Trapp Family in Stowe, Killington and I'm certain that there's a resort in the southern Vermont mountains, but I can't remember its name. Several resorts in the Berkshires, several in the New Hampshire mountains and a few in Maine. Check out the TUG reviews.
Dick Taylor